EXPT block returns a wrong value under certain target system in case of an invalid connection

Symptom: In case of an invalid connection of the EXPT block with ANY_REAL values (see example), the block should return "Not-a-Number" (NaN). Moreover, the example checks the validity of the ANY_REAL value with the IS_VALID block because the IS_VALID block will return the value FALSE in case of "NaN".
However, this is not the case for the platform "vxWorks x86".

Example for ST-code

Example for ST-code
`FUNCTION_BLOCK ExampleExptInvalid2` `VAR` `resultRealInvalid : REAL;` `END_VAR` `resultRealInvalid:= EXPT(IN1 := REAL#-25.0, IN2 := REAL#0.5);` `(* For the built-in PLC, 'resultRealInvalid' evaluates to 'NaN' in the 'Values of Variables* view. )` `( But this is not the case for vxWorks x86. *)` `ASSERT(NOT IS_VALID(resultRealInvalid));` `END_FUNCTION_BLOCK`

FUNCTION_BLOCK ExampleExptInvalid2

VAR

   resultRealInvalid : REAL;

  END_VAR

  resultRealInvalid:= EXPT(IN1 := REAL#-25.0, IN2 := REAL#0.5);

  (* For the built-in PLC, 'resultRealInvalid' evaluates to 'NaN' in the 'Values of Variables* view. *)

  (* But this is not the case for vxWorks x86. *)

  ASSERT(NOT IS_VALID(resultRealInvalid));

END_FUNCTION_BLOCK

Workaround: none existing